Thanks very much for all your responses!
I've looked Angle Shades up in my book - the reason I didn't spot it before is because the drawing there shows it at rest with its wings in a fairly narrow 'V' shape, whereas in my photo it was fluttering its wings slightly in a broader 'V', so when i flicked through the book I was looking for the wrong shape. I'll know better next time.
WAB is working its magic, and I'm starting to take a wider interest in nature, including moths. I recognised a Garden Carpet moth a few weeks ago, so that's two down, only a few hundred more to go!
